The technology of producing composite material components or parts, which include a heat curable resin system, is polarized. At one end of the scale, there exists low cost, low quality "engineered" composites. While at the other end, high quality "advanced" composite materials are extremely costly to produce. Such advanced composite materials are highly desirable for use in many applications due to their high strength, low weight, and other beneficial physical properties. Accordingly, a genuine need exists for methods of forming advanced composite material parts at a lower cost.
One reason some advanced material composites are extremely expensive is that only high performance materials, such as kevlar or graphite, are used to produce such parts. These materials can be very expensive. Additionally, for many applications, expensive molds are required to heat the composite materials to cure a high temperature resin system impregnated in such materials. Alternatively, cumbersome heating blankets can be used. Such blankets are difficult to apply in many applications to thoroughly heat a part, and are inefficient in that much of the heat produced by such blankets is dissipated into the atmosphere. Although lower temperature resin systems can be used (i.e., ambient curing), it is difficult to consistently produce a large number of high quality parts with such systems. This is due to the fact that such systems are dependent on ambient conditions which can vary widely and disrupt the curing cycle.
One attempt to provide an improved method of curing composite material is disclosed in U.S. Pat. No. 4,560,428 to Sherrick et al. In this patent, a layer of conductive carbon or graphite fibers is placed adjacent a composite material patch which is used for repair of a parent structure. The conductive fiber layer is resistively heated to cure a resin impregnated in the patch and to trigger a heat activated adhesive to bond the patch to the parent structure. The conductive fiber layer may then be removed, or in some applications can become bonded to and form part of the patch. However, Sherrick et al. does not provide any teaching of forming a completed composite material part, separate from a parent structure, or of utilizing a composite material having a conductive layer which is integrally consolidated with the composite material prior to curing of the resin in such composite material. Further, Sherrick et al. does not disclose the use of a composite material having an integral conductive layer in as a reinforcing structure.
The composite industry needs low-cost advanced composite material parts and low-cost methods of producing such parts. The present invention provides a low-cost method of consistently producing composite material parts having desirable physical properties. Additionally, the present invention also provides unique low-cost composite materials for use in such methods.